直接说解决方案
// 弹框打开时
fixedBody = () => {
const scrollTop = document.body.scrollTop || document.documentElement.scrollTop;
document.body.style.setProperty('position', 'fixed');
document.body.style.setProperty('top', `${-scrollTop}px`);
};
// 关闭时
resetBody = () => {
document.body.style.setProperty('position', '');
document.documentElement.scrollTop = -parseInt(document.body.style.top);
};